1. Field of the Invention
The present invention refers to a therapeutic mattress, in particular for preventing or curing decubitus ulcers. The decubitus ulcer is not an independent illness but develops secondarily to a primary illness that forces the patient into immobility. It develops invariably against the background of a protein deficiency syndrome, a consequence of malnutrition frequently found in the aged. This deficiency affects the mechanical properties of the patient's bodily tissues, which thus become less resistant to the pressures they are subjected to as the weight of the patient's body presses such tissues against the mattress the patient is lying on. Such ulcers are very common in the chronically ill and represent feared complications frequently more dangerous than the primary illness itself. Once developed, the wound gets easily infected and must be treated against such infections. Also, the mattresses to be used for such patients are designed to make the patient's total body weight relatively uniformly distributed on the surface of the mattress, to make the specific pressure at any one point of the skin as small as possible, to prevent any further damage to the tissue. In addition, the time during which the pressure acts on a particular region of the skin is kept within allowable limits by moving the patient periodically and keeping his exposure compatible with the status of his tissues. These measures must be applied in all cases in which a decubitus ulcer has already developed if a cure thereof is endeavoured, but they are advisable if only the prevention of such ulcers is aimed at.
2. Description of the Prior Art
Known therapeutic mattresses of the aforementioned kind are excessively soft. One such known mattress having a height of about 20 cm is referred to as alternating pressure mattress and is composed of two parts tapered in cross-section and disposed on top of each other, and is arranged to have cushions individually inflatable and deflatable. On this mattress is placed a very soft second mattress of a thickness of 12 to 15 cm. These alternating pressure mattresses have not been very successful. On the one hand, they are too high when used together with the stated second mattress. On the other hand, they do not properly adapt to a class of bed frames that comprise hinges extending perpendicular to the longitudinal direction of the bed to form a head wedge and a foot wedge. Also when deflating one of the mattress components, the patient will be in danger of rolling out of bed, or of rolling against the safety grid that may be provided.